Hydraulic winch control mechanism



y 3, 1966 E. c. BROWN ETAL 3,249,336

HYDRAULIC WINCH CONTROL MECHANISM Filed June 18, 1963 2 Sheets-Sheet 1 53 I 56 f. z 27 14110 22 E a I II I 'HIH H wmi I 33 38 INVENTORS Eowm C. BROWN BY GRANVILLE WOOLMAN Ar-rvs,

E- C. BROWN ETAL HYDRAULIC WINCH CONTROL MECHANISM May 3, 1966 2 Sheets-Sheet 2 Filed June 18, 1963 F NQ n9 mm 2. J R M a $3 mm W W a g F..J\|l manna .N. g R 3w -T N 0:2 M ST w G :T v Nw m. J l M I- E ww I m2 [IL w INVENTORS Eowuv C. BROWN BY GRANVILLE WWLMAN LJW Van/(2M A-rrvs.

United States Patent 3,249,336 HYDRAULIC WINCH CONTROL MECILANISM Edwin C. Brown, Aurora, and Granville Woolman, Naperville, Ill., assignors t0 Baldwin-Lima-Hamilton Corporation, a corporation of Pennsylvania Filed June 18, 1963, Ser. No. 288,795 Claims. (Cl. 254-150) This invention relates generally to cable winch mechanisms and more particularly concerns a hydraulic winch control'mechanism for a cable winch mounted on a rotatable crane boom.

In recent years self-propelled vehicle cranes have become increasingly popular for performing a great variety of tasks. These vehicles typically have a crane boom mounted on a vehicle chassis with means for both elevating one end of the boom and for rotating the boom through all or a substantial portion of a complete circle. A cable winch is usually mounted at the rear end of such a boom for taking up and paying out cable to respectively raise and .lower a load supported by the projecting endof the boom.

Frequently these cable winches have been powered by a hydraulic motor through a self-locking worm gear drive. Such self-locking worm drives, of course, obviate the necessity for an independent braking mechanism for the Winch drum. However, these worm drives are very. ineflicient at running speed, and even more ineflicient when starting under load. While many attempts have been made to increase the efiiciency of the winch driving mechanism, these attempts usually necessitate the addition of a separate brake mechanism for the winch "and also the incorporation of elaborate controls for the winch brake. Moreover, the brake control mechanisms usually increase the complexity of the operating controls, resulting in both operator confusion and inefficiency. In addition, these mechanisms often require frequent servicing and attention, thus increasing both the maintenance cost and, the down-time of the crane.

Accordingly, it is the primary aim of the present invention to provide a'hydraulic winch control mechanism which afI'ords both high running and starting efiiciency and yet which is simple to operate and control.

It is a more particular object to provide a hydraulic winch control mechanism having a self-locking brake mechanism which is automatically disengaged when the cable is taken up or payed out. A related object is to provide for the operation and control of both the winch brake and the winch motor by the manipulation of a single remotely located control lever.

Another object is to provide such a hydraulic control mechanism which permits dynamic braking of the winch motor when the cable on the winch drum is being payed out.

It is a further object to provide a control mechanism of the above type in which the winch drum may be selectively disengaged from the drive motor through a remotely operated control to permit the free-drop of the load when desired.

Yet another object is to provide a winch control mech- ;anism for a crane-type vehicle having the above mentioned features in which the control elements are hydraulically operated from the sources of hydraulic pressure fluid normally found on such vehicles.

Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:

FIGURE 1 is a perspective view of a crane-type vehicle in which the hydraulic winch control mechanism of the present invention is embodied;

FIG. 2 is a schematic diagram of the hydraulic control system; and

ice

FIG. 3 is an enlarged schematic diagram with some portions in section illustrating the internal construction of the actuating elements and automatic valving.

While the invention will be described in connection with certain preferred embodiments, it will be understood that we do not intend to limit the invention to those embodiments. On the contrary, we intend to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

Turning now to the drawings, there is shown in FIGURE 1 a conventional crane-type vehicle 10 in which the hydraulic winch control mechanism of the present invention is incorporated. The crane 10 includes a chassis 11 which is supported by front wheels 12 and rear wheels 13. Preferably, both the front and rear wheels are steerable, and a steering wheel 14 and tiller bar (not shown) are located adjacent an operators platform 15 at the forward end of the crane chassis 11. In addition, the front wheels 12, as well as the rear wheels 13, are driven by a motor 16 mounted on the rear portion of the crane chassis. Thus, it will be understood that the crane 10 is a very maneuverable four-wheel drive and four-wheel steer vehicle.

Located substantially centrally between the front and rear wheels 12, 13 is a boom and shipper support structure 17 which is rotatably mounted on the crane chassis 11. The support structure 17 pivotally mounts a boom shipper 17a in which a telescoping boom 18 is slidably mounted. Preferably, the boom and shipper are adapted to be hydraulically'raised and lowered. In the present instance this is accomplished by a pair of hydraulic cylinders 19 which interconnect the support structure 17 and the shipper 17a. Journalled at the forward end of the boom 18 is a pulley 20 over which a cable 21 is trained to support a hook block 22. A cable winch mechanism, indicated generally at 23, is mounted on the rear end portion of the boom for taking up and paying out the cable 21 in order to raise and lower the book block 22.

At each corner of the crane chassis 11 there is mounted a power operated outrigger 24. As seen in FIG. 1, the outriggers are positioned in their upraised, or transport positions. It will be understood, however, that the outriggers may be lowered into ground engaging contact to relieve the load on the wheels 12, 13 and to provide a more stable operating base for the crane 10 when lifting a heavy load. The outriggers are preferably independently operated by hydraulic actuators (not shown) under control of separate operating control levers 25 located adjacent the operators platform 15.

In the illustrated crane 10, an actuator (not shown) is provided for hydraulically extending and retracting the telescopic boom 18, as well as raising and lowering the boom, as mentioned above. Moreover, the boom 18 and its support structure 17 are also rotatable through a complete circle by means of a hydraulic motor (not shown), which is mounted on the crane chassis 11. The winch mechanism 23 is preferably driven by a reversible hydraulic motor 26 mounted on the boom 18. To control the various functions of raising and lowering, extending and retracting, and rotating the boom in either direction, as well as reversibly driving the winch motor 26,

separate control levers 27 are provided within easy reach of the crane operator adjacent the operators platform 15. Thus, it will be appreciated that the crane 10 is an extremely versatilehydraulically controlled mechanism .which has great flexibility of operation.

Diagrammatically illustrated in FIG. 2 is a portion of the hydraulic control and distribution system 30 for the crane 10. It will be understood by those familiar with this art that a reservoir 31 is located on the crane chassis 11 in order to provide a source of hydraulic pressure fluid for the various hydraulic actuators of the crane. A hydraulic pump 32, also located on the crane chassis, has a supply line 3-3 communicating with the reservoir to deliver hydraulic pressure fluid to the actuators for moving the crane boom 18 and hook block 22 through a wide range of operating positions. It will also be understood that each of the actuators is controlled by manipulation of one of the respective control levers 27, which operate a series of control valves 34 coupled to an output line 35 from the pump 32. The winch motor 26 is controlled, for example, by control valve 34a and the selective pressurization of control lines 36 and 37. A return line 38 is coupled between the valves 34 and the reservoir 31 for returning hydraulic fluid to the reservoir.

To permit full-circle rotation of the crane boom 18 and support structure 17 on the chassis 11, while still affording selective hydraulic control of the winch motor 26, a rotary hydraulic distributor 40 is coupled between the winch motor 26 and the winch control valve 34a. The rotary distributor 40 includes a lower stationary portion 41 secured tothe crane chassis 11 and an upper rotatable portion 42 which is preferably coaxially mounted within the support structure 17 with respect to the vertical axis of rotation of the support structure. It will also be understood that the rotary distributor defines separate passages 43 and 44 which are respectively coupled to the hydraulic control lines 36, 37 leading from the winch control valve 34a. As shown in FIG. 2, the elements of the control system 30, which are stationary with respect to the chassis 11, are indicated generally at 45 below line A; and conversely, elements of the control system, which are mounted on the boom shipper 17a are indicated generally at 46 above the line A.

For selectively taking up and paying out the cable 21, the winch mechanism 23 includes a cable drum 51 about which the cable is wound. The drum 51 is mounted on and drivingly coupled to a transverse drum shaft 52 which is journalled at the rear end portion of the boom shipper 17a. Preferably, the shaft 52 is driven through a planetary gear reduction unit 53 having non-locking intermediate gears or internal elements 54. The gear reduction unit 53 is driven by the winch motor 26 through a drive shaft 56 and bevel gears 57 and 58, respectively mounted on the drive shaft and reduction unit 53.

To drive the winch motor 26 in either direct-ion, a pair of reversible supply-return lines 61 and 62 are coupled to the motor and the rotary distributor 40 for supplying hydraulic pressure fluid from the control lines 36, 37. It will be understood that the first hydraulic supply-return line 61 is effective when pressurized through the control line 37 and passage 44 for driving the motor 26 in one direction, for example to take up the cable 21, upon suitable manipulation of the control valve 34a. Conversely, the second supply-return line 62 is effective when pressurized for driving the motor 26 in the opposite, or cable paying out direction. Thus, by manipulation of the remotely located control valve 340, the flow of hydraulic pressure fluid is selectively admitted and reversed through the first and second hydraulic lines 61, 62 to operate the winch motor 26 in either direction.

When the cable 21 is taken up on the winch drum 51 by selectively pressurizing the line 61 to drive the motor 26in one direction, it will be understood that the hook block 22 is raised from the projecting end of the boom 18. On the other hand, when the cable is payed out from the drum, by driving the motor in the opposite direction, the hook block is lowered. It will also be appreciated that when the first hydraulic supply line 61 is pressurized to drive the motor in one direction, the second hydraulic line 62 returns the hydraulic pressure fluid from the motor 26 to the reservoir 31. Conversely, the pressurization of the second hydraulic line 62 to drive the motor 26 in the opposite direction requires the first hydraulic line 61 to function as a return line.

For resisting movement of the winch drum 51 when the motor 26 is not operated, a brake mechanism 65 is provided. The brake 65 serves to oppose the torque exerted on the drum shaft 52 due to a heavy load supported by the cable 21, a portion of which is wrapped about the winch drum 51. It will be understood that, since the gear reduction unit 53 is constructed with non-locking gears or elements 54, substantially all of the torque on the winch drum 51 is transmitted through the drum shaft 52 to the motor drive shaft 56.

In the illustrated embodiment, the brake mechanism 65 is mounted on the boom shipper 17a (see FIG. 1) and is coupled to the winch mechanism 23 through the drive shaft 56 of the motor 26. Thus, as shown in FIG. 2, a brake drum 66 is rigidly mounted on the shaft 56 intermediate the motor 26 and the gearv reduction unit 53. Closely surrounding the brake drum 66 is an arcuate brake shoe 67 which is adapted to frictionally engage the brake drum and thus resist the torsional forces which are exerted on the cable winch 23. It will be understood, of course, that brake mechanisms of other types may also be utilized and they may be coupled to the winch 23 through other means without departing from the present invention.

In the exemplary construction, the brake 65 is biased into locked position and a hydraulic actuator 68 is coupled to the brake for releasing the brake shoe 67. As seen in FIG. 3, the actuator includes a hydraulic cylinder 69 in which a piston 70 is slidably mounted. The piston 70 is coupled by an operating rod 71 to one end 72 of the brake shoe 67, and the other end 73 of the brake shoe is engaged by an elongated body portion 74 of the acutator 68. Within the body 74, a compression spring 75 is coaxially mounted to normally bias the brake shoe 67 into engagment with the brake drum 66. The running clearance of the brake mechanism 65 may be adjusted by turning a pair of lock nuts 76- and 77 so as to alter the effective length of the operating rod 71. To operate the brake release actuator 68, hydraulic pressure fluid is admitted to the cylinder 69. The resulting upward movement of the piston 70' (from the position shown in FIG. 3), compresses the spring 75 and expands the brake shoe 67 to disengage the brake drum 66.

In accordance with the present invention, the brake 65 is rendered inoperative incident to operation of the winch motor 26 in either direction. For this purpose, hydraulic pressure fluid is communicated to the actuator 68 upon the pressurization of either the first or second hydraulic supply-return lines 61,62. To direct hydraulic fluid to the actuator 68,'a brake supply line 78 is coupled through a bidirectional shuttle'valve 80 to the first and second supply-return lines 61, 62 of the winch motor 26. Thus, the brake 65 is automatically released whenever the remotely located control valve 34a is manipulated to selectively operate the motor 26 for taking up or paying out the cable 21 from the winch mechanism 23.

The shuttle valve 80 is formed with a body 81 which defines a cylindrical bore 82 in which a bidirectional spool 83 is slidably mounted. The bore 82 is formed with a series of annular grooves or ports 85, 86, 87 and 88, each separated from the adjacent ports by suitable lands. The axially slidable spool 83 is fitted within the bore 82 so as to sealingly engage the lands in the bore- Reduced portions 89,90 and 91' on the spool 83 provide for establishing communication between various ones of the valve ports -88 as the spool is shifted to different positions.

As shown in FIG. 3, the spool 83 of the exemplary valve 80 is normally centered within the bore 82 by a pair of compression springs 93 and 94. The valve body 81 also defines apertures 95 and 96located adjacent its opposite ends and to which branches 61a and 62a of the hydraulic lines 61, 62 are respectively coupled. It will be understood that the apertures 95, 96 communicate hydraulic fluid to the bore 82 at opposite ends of the spool 83 which are preferably formed to define piston portions with substantially equal areas.

Opposite the apertures 95, 96 the valve body 81 defines another aperture 97 which is coupled to the supply line 78 of the brake actuator 68. Coaxial with the aperture 87 is an elongated passageway 98 formed to communicate with the ports 85, 86 and 88 formed in the cylindrical bore 82. Intermediate the apertures 95, 96 another aperture 99 is formed in the body 81 so as to communicate with the port 87. Thus, as shown in FIG. 3, the aperture 97 is placed in communication with the aperture 99 by the ports 86 and 87 in the valve bore 82 and the reduced portion 96 in the spool 83. The aperture 99 is coupled to a return line 101 which exhausts hydraulic pressure fluid from the actuator 68 to a bleed line 102 which carries the hydraulic leakage from the Winch motor 26 through the rotary distributor 40, back to the reservoir 31.

When the hydraulic line 61 is pressurized to drive the winch motor 26 in one direction, the branch line 61a is also pressurized thereby causing the spool 83 of the shuttle valve 80 to shift to the right from the position shown in FIG. 3. With the spool 83 in its right hand position, the port 88 is uncovered to communicate hydraulic pressure from the aperture 95 through the passage 98 and aperture 97, to the actuator cylinder 69. The increase of pressure fluid in the cylinder 69, of course, shifts the piston 70 upward from the position shown in FIG. 3 to release the brake mechanism 65. When the pressurization of hydraulic line 61 is terminated upon returning control valve 34a to its neutral position, the spool 83 immediately shifts to its centered position, as illustrated in FIG. 3, whereby hydraulic fluid is exhausted from the actuator cylinder 69 through the passage 98 and out through return line 101 to the reservoir 31. Thus, the brake mechanism 65 is immediately actuated by the spring 75 so that the brake shoe 67 engages the brake drum 66 to resist movement of the winch mechanism 23.

Operation of the winch motor 26 in the opposite direction, that is by the pressurization of hydraulic line 62,

causes the valve spool 83 to shift to the left from the position shown in FIG. 3. When the spool 83 is in its left hand position, the port 85 is uncovered permitting hydraulic fluid to flow through the passage 98 to the actuator 68. Upon the termination of the pressurization of the line 62, the valve spool 83 immediately shifts back to its centered or neutral position thereby allowing hydraulic fluid to exhaust from the actuator 68 through the return line 101. To facilitate the rapid centering of the spool 83, a small central passageway 103 is formed in the spool to neutralize the residual pressure at either end of the spool.

Pursuant to another feature of the present invention, provision is made in the hydraulic control system 30 to dynamically brake the winch motor 26 when a load is lowered by the hook block 22. To this end, a counterbalance valve 110 is interposed in the hydraulic supplyreturn line 61. The counterbalance valve 110 defines a valve seat lll-inwhich a valve stem 112' is slidably mounted. As shown in FIG. 3, the valve stem 112 defines a plurality of axially spaced peripheral openings 113 which are graduated from smaller to larger sizes progressively from the top toward the bottom of the stem 112. The lower portion of the stern 112 is disposed withIn a chamber 114 to which the supply-nturn line 61 is connected. Thus, when line 61 is pressurized, the valve stem 112 is raised off the seat 111 and pressure fluid flows freely through the openings 113.

To retain the valve stem 112 in its seated position, as shown in FIG. 3, a compression spring 116 is coaxially mounted with the stem 112 and is biased against a plug 117 closing the upper end of the valve 110. Intermediate the plug 117 and stem 112 a chamber 118 is formed in the valve to communicate the hydraulic pressure fluid through another section of the line 61 to the winch motor 26.

.trol of the winch motor 26 as described above.

When the control valve 34a is moved to its load lowering position, that is to pressurize hydraulic line 62, the reverse flow of hydraulic fluid through line 61 is restricted by the counterbalance valve thereby dynamically braking the motor 26. The extent of dynamic braking is dependent upon the pressure of the hydraulic fluid in supply-return line 62. This pressure is communicated to the counterbalance valve 110 through a branch line 62b coupled to an orifice 121 in the lower portion of the valve 110.

For raising the valve stem 112 from the seat 111 during dynamic braking of the motor, a rod 122 is coupled to a piston 123 slidably mounted in a cylinder 124 in communication with the orifice 121. The number of peripheral openings 113 in the valve stem 112 which are uncovered is, of course, dependent upon the diflerence in force exerted on the piston by the hydraulic pressure in line 62b and the exhaust force on the valve stem 112 from the line 61. Due to the differential area of the piston 123 and the valve stem 112 and the graduated nature of the openings 113, the dynamic braking of the motor- 26 can be closely controlled by operation of the control valve 34a. In this way, it will be seen that the torque exerted on the motor 26 by the winch mechanism 23 while low ering a load is effectively countered by the dynamic braking provided by the counterbalance valve 110.

It is another feature of the present invention that the Winch drum 51 may be disengaged from the drum shaft 52 through a remotely operated control to permit the free-drop of a load supported by the hook block 22 when desired. As shown in FIG. 2, a clutch mechanism is mounted on the end of the drum shaft 52 opposite the gear reduction unit 53. In the illustrated embodiment, the clutch 130 includes a clutch plate 131 secured by a key 131a to the shaft 52, and a pair of clamptype shoes 132 mounted on a carrier frame 133 secured to the drum 51. It will be understood that when the shoes 132 are disengage-d from the face of the clutch plate 131, the frame 133 and winch drum 51 are free to rotate about the shaft 52 on which they are journalled and thus the cable 21 is freely payed out.

To engage and disengage the clamp-type shoes 132 and clutch plate 131, a pair of actuators 134 are mounted on the frame 133, one actuator being coupled to each shoe by an operating rod 135 and lever 136 (only one of which is shown in FIG. 3). Normally, the shoes 132 are biased into engagement with the plate 131 by a pair of heavy compression springs 137. Preferably, the springs 137 are coaxially mounted on the operating rods 135 which extend from the actuators 134. Thus, in its normal condition, the clutch 130 is engaged and the winch drum 51 is drivingly coupled to the drum shaft 52 under con- If the free-drop provision is not incorporated, the drum 51 can, of course, be splined directly to the shaft 52.

When free-drop of a load supported by the hook block 22 is desired, the shoes 132 are disengaged from the plate 131 by the actuators 134. The actuators in the present instance are each formed with a cylinder 138 in which a piston 139 is slidably mounted. The pistons 139 are coupled to the operating rods 135 for swinging the lovers 136 against the compressive force of the springs For remotely controlling the clutch mechanism 130, a suitable operating control or pedal 140 is located on the crane chassis 11, preferably adjacent the operators station 15. The pedal 140 is coupled to a hydraulic master cylinder 141 which is provided with a suitable source of hydraulic fluid. An output line 144 delivers the pressurized hydraulic fluid from the master cylinder to the rotary distributor 40. Thus, as shown in FIG. 2, the control pedal 140 and cylinder 141 form part of the stationary control system 45, indicated below the line A. It will be understood that the rotary distributor 40 defines a pas- 7 sageway for the pressurized fluid delivered by the cylinder 141.

Above the crane chassis 11, a distribution line 145 is coupled to the rotary portion 42 of the distributor 40. To prevent unnecessary flexing of the line 145 a swivel coupling 146 is provided adjacent the horizontal axis of the boom 18. Another swivel coupling 147 is also mounted coaxially with the drum shaft 52 in order to permit efllcient distribution of pressurized hydraulic fluid to the actuators 134 which are adapted to rotate about the shaft 52 on the frame 133. Branch lines 148 and 149 communicate hydraulic fluid from the swivel coupling 147 to the cylinders 138 of the actuators.

From the foregoing, it will be appreciated that the various functions of the Winch mechanism 23 can be easily and conveniently controlled from the operators station 15 through the novel hydraulic distributor system 30 of the crane 10. Thus, in the static condition shown in the drawings, the clutch 130 is engaged to secure the winch drum 51 to the drum shaft 52. In addition, the brake mechanism 65 is normally biased to engage the drive shaft 56 which interconnects the motor 26 and the planetary reduction unit 53 of the winch 23. By simply manipulating one of the levers 27 for the valve 34a, the operator can selectively raise or lower the hook block 22 by appropriately hydraulically driving the motor 26 to rotate the winch drum 51 so as to take up or pay out the cable 21.

When the motor 26 is driven in either direction by the pressurization of either of the supply-return lines 61, 62,

the brake mechanism 65 is automatically disengaged under control of the shuttle valve 80. To control the lowering of a load supported by the hook block 22, the motor 26 is dynamically braked through the counterbalance valve 110. Alternatively, the load may be free-dropped by disengaging the clutch 130 so as to allow the winch drum 51 to rotate freely on the shaft 52 and pay out the cable 21. This latter function is also remotely controlled by the operator through the pedal 140 located adjacent the operators station 15 on the crane chassis 11.

It will also be appreciated that since both the brake mechanism 65 and clutch 130 are normally biased into engagement with their respective shafts, the hydraulically actuated controls are free from most normal maladjustments which typify the conventional mechanically linked controls. In addition, the simplicity of the present contr-ol system 30 affords significant savings in maintenance time and costs and insures that the down-time of the crane 10 is essentially eliminated.

We claim as our invention:

1. A control mechanism for a remotely operated cable winch on a rotatable crane boom comprising, in combination a reversible hydraulic motor mounted on said boom and coupled to said Winch for selectively taking up and paying out the cable therefrom, said motor having a pair of hydraulic supply and return lines coupled thereto, a source of hydraulic pressure fluid located remotely from said boom and said motor, a rotary distributor defining separate passages for each of said hydraulic lines interposed between said source and said motor, a control valve for selectively admitting and reversing the flow of hydraulic pressure fluid through said hydraulic lines, a brake mechanism mounted on said boom and coupled to said winch for stopping movement thereof when said motor is not operated, said brake mechanism having a hydraulic actuator for disengaging said brake, and means including a shuttle valve for communicating hydraulic fluid to said actuator under the influence of a pressure dilferential in said lines to render said brake mechanism inoperative incident to operation of said motor in either direction, said shuttle valve being connected between each of said hydraulic lines and said actuator and including a bidirectional slide element with substantially equal areas on its opposite ends.

2. A control mechanism as defined in claim 1 including biasing means for normally centering said slide element within said shuttle valve, said slide element being operative to shift to said centered position to bleed pressure fluid from said actuator upon equalization of pressure in saidhydraulic lines whereby said brake mechanism is immediately actuated.

3. A control mechanism as defined in claim 1 including a counterbalance valve interposed between one of said hydraulic lines and said shuttle valve for permitting the free flow of hydraulic pressure fluid in one direction to drive said motor and for restricting the discharge of hydraulic pressure fluid from said motor in the opposite direction to dynamically brake said motor.

4. A control mechanism as defined in claim 1 including a chassis supporting said rotatable crane boom, a drum shaft journalled for rotation on said boom, a Winch drum mounted on said shaft for taking up and paying out cable therefrom incident to rotation in opposite directions, a spring biased clutch mechanism for coupling said shaft in driving relation to said drum, said clutch mechanism having an actuator thereon for disengaging said drum from said shaft whereby said drum is freely rotatable to pay out the cable therefrom, and control means located on said chassis for selectively energizing said actuator.

5. A control mechanism as defined in claim 1 including a drum shaft journalled for rotation on said boom, said drum shaft having a clutch plate secured thereto, a winch drum mounted on said shaft for taking up and paying out cable therefrom incident to rotation in opposite directions, said drum having a frame secured thereto carrying a pair of clamp-type shoes, means for normally biasing said shoes into engagement with said plate so as to couple said shaft in driving relation to said drum, and an actuator for disengaging said shoes from said plate whereby said drum is freely rotatable about said shaft to pay out the cable therefrom.

References Cited by theExaminer UNITED STATES PATENTS 2,176,468 10/1939 Morin.

2,606,745 8/1952 Ball 254l66 2,945,572 7/1960 Rye 1923 3,107,899 10/1963 I-Ienneman 254187 3,112,035 11/1963 Knight 21235 3,120,880 2/1964 Iaseph 187l7 3,128,861 4/1964 Trondsen 254--187 EVON C. BLUNK, Primary'Examiner.

SAMUEL F. COLEMAN, Examiner.

H. HORNSBY, Assistant Examiner. 

1. A CONTROL MECHANISM FOR A REMOTELY OPERATED CABLE WIND ON A ROTATABLE CRANE BOOM COMPRISING, IN COMBINATION A REVERSIBLE HYDRAULIC MOTOR MOUNTING ON SAID BOOM AND COUPLED TO SAID WINCH FOR SELECTIVELY TAKING UP AND PAYING OUT THE CABLE THEREFROM, SAID MOTOR HAVING A PAIR OF HYDRAULIC SUPPLY AND RETURN LINES COUPLED THERETO, A SOURCE OF HYDRAULIC PRESSURE FLUID LOCATED REMOTELY FROM SAID BOOM AND SAID MOTOR, A ROTARY DISTRIBUTOR DEFINING SEPARATE PASSAGES FOR EACH OF SAID HYDRAULIC LINES INTERPOSED BETWEEN SAID SOURCE AND SAID MOTOR, A CONTROL VALVE FOR SELECTIVELY ADMITTING AND REVERSING THE FLOW OF HYDRAULIC PRESSURE FLUID THROUGH SAID HYDRAULIC LINES, A BRAKE MECHANISM MOUNTED ON SAID BOOM AND COUPLED TO SAID WINCH FOR STOPPING MOVEMENT THEREOF WHEN SAID MOTOR IS NOT OPERATED, SAID BRAKE MECHANISM HAVING A HYDRAULIC ACTUATOR FOR DISENGAGING SAID BRAKE, AND MEANS INCLUDING A SHUTTLE VALVE FOR COMMUNICATING HYDRAULIC FLUID TO SAID ACTUATOR UNDER THE INFLUENCE OF A PRESSURE DIFFERENTIAL IN SAID LINES TO RENDER SAID BRAKE MECHANISM INOPERATIVE INCIDENT TO OPERATION OF SAID MOTOR IN EITHER DIRECTION, SAID SHUTTLE VALVE BEING CONNECTED BETWEEN EACH OF SAID HYDRAULIC LINED AND SAIC ACTUATOR AND INCLUDING A BIDIRECTIONAL SLIDE ELEMENT WITH SUBSTANTIALLY EQUAL AREAS ON ITS OPPOSITE ENDS. 